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New Treatments for Chronic Paroxysmal Hemicrania

This headache resembles cluster headache in character but distinguishes itself by its dramatic responsitivity to indomethacin therapy. The pathophysiology of chronic paroxysmal hemicrania is unknown. Changes in intraocular pressure that occur during attacks suggest autonomic dysfunction, and the periodicity of this disorder suggests a central generator. Chronic paroxysmal hemicrania is a rare disorder that affects women more than men.

Like cluster headache patients, chronic paroxysmal hemicrania patients have severe unilateral headache associated with unilateral nasal stuffiness, lacrimation, conjunctival eye tearing, ptosis, and eyelid edema. Headaches average 13 minutes in duration and occur an average of 11 times a day. Occasionally, there is a continuous dull ache between attacks. In 10 percent of patients, attacks may be triggered by flexing, rotating, or pressing the upper portion of the neck.

Rarely, a patient may present with episodic paroxysmal hemicrania with remissions lasting weeks or months. Patients may evolve from the episodic to the chronic form of the illness. By definition chronic and episodic hemicrania are responsive.

No other medical or psychiatric disorders have been associated with chronic paroxysmal hemicrania. The differential diagnosis of chronic paroxysmal hemicrania is similar to that of cluster headache. In addition, patients with "jabs and jolts syndrome" might occasionally resemble chronic paroxysmal hemicrania patients. A rare headache disorder called short unilateral neuralgiform headache with conjunctival injection and tearing should be considered, although the headaches are much shorter in duration (15 to 30 seconds) and occur much more frequently (many times per hour) than those of chronic paroxysmal hemicrania.

In the evaluation of chronic paroxysmal hemicrania, a trial of indomethacin is necessary to establish the diagnosis. Brain imaging with MRI or CT should be undertaken to exclude symptomatic causes of apparent chronic paroxysmal hemicrania. The treatment of choice is indomethacin (up to a dose of 200 mg per day). Aspirin may also be beneficial, but the relief afforded is usually not complete. Chronic paroxysmal hemicrania may last indefinitely, but over time.

Temporary remissions and spontaneous cures have been described. Selective prostaglandin synthesis inhibitors, indomethacin-like drugs without the gastrointestinal side effects of the current NSAIDs, are in development.

Idiopathic Intracranial Hypertension

Pathogenesis and Pathophysiology. The pathophysiology of IIH is unknown. Postulated mechanisms include increased CSF production, decreased CSF absorption, and increased venous sinus pressure. Some studies suggest that interstitial brain edema and a decreased rate of absorption at the arachnoid villi are the major contributors. The disturbances of CSF hydrodynamics in IIH persist for years. Increased CSF pressure in IIH may result from a rise in venous sagittal sinus pressure secondary to extracellular edema causing venous obstruction, or from low conductance for CSF reabsorption producing a compensatory increase in CSF pressure.

Epidemiology and Risk Factors. IIH with papilledema occurs with a frequency of about one case per 100,000 per year in the general population and 19.3 cases per 100,000 per year in obese women aged 20 to 44. The patient with IIH is commonly a young, obese woman with chronic daily headaches, normal laboratory studies, an empty sella, and a normal neurological examination (except for papilledema).

Clinical Features and Associated Disorders. The symptoms of IIH consist of generalized increased intracranial pressure, with headache occurring in most, but not all, patients. Bifrontotemporal headache is most common. Unilateral headache with increased CSF pressure due to IIH may be an exacerbation of migraine or a new local phenomenon. Transient visual obscuration, an episode of visual clouding in one or both eyes usually lasting seconds, occurs with all forms of increased intracranial pressure with papilledema but is not a specific symptom. Transient visual obscurations can occur in patients without increased intracranial pressure who have elevated optic discs from other causes. Persons without papilledema do not have transient visual obscurations. Pulsatile tinnitus, diplopia, and visual loss can occur. Some patients report shoulder and arm pain (perhaps secondary to nerve root dilatation) and retro-orbital pain.

IIH without papilledema has been described in some patients. The headache and demographic characteristics are identical to those of patients with papilledema except for (1) possible association with prior head trauma or meningitis; (2) extended delay in diagnosis, which requires lumbar puncture in the absence of papilledema; and, (3) no evidence of the visual loss seen in patients with IIH with papilledema.There are no disorders associated with IIH other than obesity.

Differential Diagnosis. IIH may be either (1) truly idiopathic, with no clear identifiable cause, or (2) symptomatic, a result of venous sinus occlusion, radical neck dissection, hypoparathyroidism, vitamin A intoxication, systemic lupus erythematosus, renal disease, or drug side effects (nalidixic acid, danocrine, steroid withdrawal).

Evaluation. The diagnosis of IIH (with or without papilledema) is based on lumbar puncture following neuroimaging (paying attention to empty sella and sinus thrombosis). If CSF biochemical and cytological analyses are unremarkable and intracranial pressure is elevated to greater than 200 mm H2 O (in nonobese subjects), IIH is the likely diagnosis. Secondary causes should also be considered in the evaluation. Over 50 diseases, conditions, toxins, or pharmaceuticals have been associated with IIH. Patients, particularly obese women, with chronic daily headaches and symptoms of increased intracranial pressure, for example, pulsatile tinnitus, a history of head trauma or meningitis, an empty sella.